RU2036041C1 - Stamped blank moulding method and apparatus - Google Patents

Abstract

FIELD: production of pieces, made from stamped blanks. SUBSTANCE: initially flange of blank is placed between deforming punch and deforming die. Peripheral part of flange is pressed along its limited width and central part of blank flange is clamped. Then, using definite contour, central part of blank flange is moulded by placing of blank flange middle fibre in specific position in respect to neutral fibre of punch-die joint till appearance at least in limited zone of blank flange of controlled inner tension. Then on free part of blank flange they exercise longitudinal bending, controlled and oriented by relocation of blank flange Peripheral part, preserving constant thickness and diameter of blank flange, with simultaneous turning of Peripheral part of blank flange to make bent edge. In process of longitudinal bending of blank flange free part deformation of the free part is oriented. Apparatus has deforming punch and die and also upper and lower pressing tools. Apparatus has joints of radial and vertical motion of pressing tools, that have wedges with several wedge surfaces and sliders with wedge areas. Upper and lower pressing tools have wedge surfaces. Apparatus has mean to control longitudinal bending and blank flange peripheral part along side walls of punch or die. Apparatus also has deformed V-shaped plate, that influences on the peripheral part of blank. The plate rests at punch-die joint and pressing tool. The plate is provided with means of its relocation and clamping in process of moulding. EFFECT: method and apparatus are used in production of pieces, made from stamped blanks.

Description

 The invention relates to the processing of metals by pressure, in particular to methods and devices for manufacturing a mask of a cathode tube.

 A known method of forming a sheet billet by drawing out the central part of the billet and acting on the flange, as well as a device for its implementation, containing a matrix, a punch, mounted on the upper plate by means of a beam, and an annular clip.

 A disadvantage of the known method and device is the low quality of products such as a mask of the cathode tube due to the formation of folds on the side surface.

 The objective of the invention is to provide a cold stamping method for sheet blanks, which in one operation implements the bending of the central part and bending down or up the peripheral zone of the sheet blank without deformation of the perforated mesh.

 For this, in the method of forming a sheet blank by drawing the central part of the workpiece and acting on the flange, the latter is placed between the deformable punch and the deformable matrix, the peripheral part of the workpiece flange is pressed at a limited width, the central part of the workpiece flange is clamped, the central part of the workpiece flange is formed along a certain contour by establishing the middle fiber of the workpiece flange in a specific position with respect to the neutral fiber of the punch-matrix assembly until at least at least, in limited areas of the workpiece flange of controlled internal stress, a longitudinal bend is carried out on the free part of the workpiece flange, controlled and oriented by moving the peripheral part of the workpiece flange, while maintaining a constant thickness and perimeter of the workpiece flange, and at the same time, the peripheral zone of the workpiece flange is deployed to obtain a bent edge, when this in the process of longitudinal bending of the free part of the workpiece flange orient the deformation of the free part.

 In the device for forming a sheet blank containing a matrix, a punch fixed to the upper plate by means of a beam, and an annular peripheral clip, the matrix and punch are made of a deformable material, and the device is equipped with a node for radial bias of the clip, a node for vertical bias of the clip, and means for controlling longitudinal bending and the rotation of the peripheral part of the workpiece flange along the side walls of the punch or die.

 In the proposed device, the peripheral clamp consists of the lower clamp and the upper clamp mounted on the traverse, the lower clamp at the level of the upper peripheral edge has a wedge surface, and the radial displacement node of the clamp consists of wedges mounted on the upper plate. The wedges have an end wedge surface and a side wedge surface for interaction with the wedge surface of the lower clip. The vertical clamp bias unit consists of creepers interacting with the wedges and a frame located between the cams and the clamp, and the creepers are movable in the direction perpendicular to the direction of movement of the wedges and have several wedge sections with different angles of inclination and orientation on their upper wall.

 The frame has a wedge surface at the level of its upper peripheral edge, with the same slope as one of the wedge surfaces of the crawler.

 The means for controlling the longitudinal bending of the peripheral part of the workpiece flange along the lateral sides of the punch is made in the form of a deformable peripheral plate, which is made in the form of a V-shaped flexible element, the first part of which rests on the punch-matrix assembly, and the second on the clamp. The first part of the deformable plate is provided with a stand in the form of a frame. The support has a vertical wall and a horizontal base adjacent to the edge of the said wall at right angles. The horizontal base of the stand has a wedge section with the same slope as the wedge section of the crawlers. The second part of the plate rests on the clamp through the pusher in the form of a vertical plate, the lower end of which is located on the horizontal base of the stand.

 The device is equipped with springs located between the vertical wall of the stand and the pusher, as well as means for blocking the matrix at bottom dead center.

 In FIG. 1 shows a sheet blank on the basis of which a cathode tube mask is made; in FIG. 2 molded mask; in FIG. 3 device in cross section; in FIG. 4 peripheral clamp of the peripheral part of the sheet blank and means for controlling the longitudinal bending of the peripheral part of the blank; in FIG. 5-11 cross sections showing successive steps of mask formation.

 In FIG. 1 shows a sheet blank 1 of very small thickness, from which a cathode tube mask is formed. The sheet blank has a Central part 2, equipped with a grid of microperforations, and a peripheral part 3 without perforations.

 The mask after molding has a central part 2 corresponding to a curved microperforation grid and a raised peripheral part 3 (Fig. 2).

 A device for forming a mask of the cathode tube contains a lower base plate 4, on which is located the base of the matrix 5, provided in the Central part of the working cavity 6.

 Above the base of the matrix 5 is placed a deformable matrix 7, which is located with its peripheral part 8 on the basis of the matrix 5.

 The matrix 7 is connected by a rod 9 with a locking system, for example, in the form of a power cylinder 10.

 The molding device also contains a deformable punch 11, mounted on an intermediate base plate 12, which is mounted on the upper base plate 13 by means of guides 14 mounted in the latter with the possibility of sliding. Between the base plates 12 and 13, compression springs 15 are inserted.

 The matrix 7 and the punch 11 are made of a deformable material, and the lower surface of the punch 11 may have a peripheral flange 16, designed to prevent slipping of the sheet 1 to the outside during the molding process.

 The upper base plate 13 supports the wedges 17, which enter the base plate 12 through the holes 18.

 Each wedge 17 has on its inner side a wedge surface 19, a vertical portion 20, and a wedge surface 21.

 The vertical stroke of the intermediate base plate 12 and the punch 11 is limited by pins 22 mounted on the lower base plate 4.

 Around the matrix 7 and the punch 11 (at the level of the plane of separation of these elements) is a peripheral clamp designed to clamp on a small width of the peripheral part 3 of the sheet blank 1. This clamp is made, for example, of composite material, consists of an upper clamp 23 and a lower clamp 24 and has a closed shape.

 The upper clamp 23 is mounted on the traverse 25, which through screws 26 located inside the oblong holes 27 provided in the upper clamp 23, provides lateral movement of the latter with respect to the traverse 25. The traverse 25 is fixed to the intermediate base plate 12 by means of guides 28 installed in the last with the ability to slip. Between the traverse 25 and the intermediate support plate 12, compression springs 29 are installed.

 The upper clamp 23 has a wedge surface 30, designed to interact with the wedge surface 21 of the wedges 17 for lateral mechanical impact on the peripheral clamp.

 The lower clamp 24 is provided with guide rods 31 designed to enter the holes 32 provided inside the upper clamp 23 with pins 33 uniformly distributed around the perimeter of the lower clamp 24, designed to center the sheet 1 and recessed in the holes 34 provided in the upper clamp 23, when the peripheral clip is closed.

 The lower clip 24 is held by a frame 35, which is supported by sliders 36, which, in turn, are supported by a lower base plate 4. The frame 35 has an external wedge surface 37.

 Each creep 36 has on its upper side a first wedge section 38, designed to interact with the wedge surface 19 of the wedges 17, a second wedge section 39, designed to interact with the wedge surface 37 of the frame 35, and a third wedge section 40, designed to interact with control means longitudinal bending.

 Springs 41 are located between the base of the matrix 5 and each creeper 36.

 The means of longitudinal bending control may consist of a peripheral deformable plate 42 inserted between the die 7 and the lower clamp 24 to orient the longitudinal bending of the peripheral part 3 of the sheet blank 1 in a uniform manner and in the same direction.

 The plate 42 is made in the form of an elastic plate, for example, of a composite material of a V-shaped flexible element.

 The first portion 43 of the plate 42 rests on a frame-shaped stand 44 and surrounds the matrix base 5. The base 44 has a vertical wall 45 in contact with the outer wall of the matrix base 5 and a horizontal base 46 adjacent to the edge of the vertical wall 45 and forming a right angle with it. The horizontal base 46 has a bottom surface 47 inclined at the same angle as the wedge portion 40 of the creepers 36.

 The second portion 48 of the plate 42 is supported by a pusher 49 formed by a vertical plate, the lower end of which lies on the horizontal base 46 of the stand 44. The springs 50 are located between the vertical wall 45 and the pusher 49 so as to keep these parts apart and supported, respectively, on the outer the edge of the base of the matrix 5 and on the inner side wall of the lower clip 24.

 In this case, the plate 42 is shown under the sheet blank 1, which leads to an increase in the edge, but the edge can be bent using a plate located above the workpiece 1 and to which the lowering movement is reported.

 The formation of the blank 1 is as follows.

 The sheet blank 1 is placed on the matrix 7 so that the small width of its peripheral edge 3 is also located on the lower clip 24 inside the area bounded by pins 33.

 A slider (not shown) of the press acts on the upper base plate 13, while the upper part of the device is lowered so as to press the punch 11 against the sheet blank 1 and lock the peripheral clamp to keep the peripheral part 3 of the blank 1 at a small width between the clamps 23 and 24. Guides rods 31 and pins 33 penetrate, respectively, into the holes 32 and 34 of the upper clamp 23.

 Under the influence of the press slider by means of support plates 12 and 13, the deformable punch 11 and the deformable matrix 7 are bent to form the necessary profile of the central part 2 of the sheet blank 1. This position is held by the power cylinder 10 at bottom dead center. The pins 22 prevent slipping of the sheet 1.

 Under the influence of the compression spring 29 and the traverse 25, the upper clamp 23 is pressed against the lower clamp 24 held in this position by the frame 35 and the ratchets 36. The peripheral part 3 of the sheet blank 1 is thus clamped.

 During this stage of the formation of the central part 2, the real median fiber of the sheet stock 1 is set to a certain position relative to the neutral fiber of the complex formed by the punch 11 and the matrix 7, so that it is possible to create, at least in the localized zones of the sheet stock 1, an adjustable internal stress for cancellation of possible stresses induced by external phenomena, such as thermal expansion and vibrations induced by acoustic, magnetic and other phenomena.

 Thus, the position of the sheet blank 1 with respect to the neutral fiber of the punch 11 matrix 7 complex can create internal tensile or compressive stresses in at least localized areas of the sheet blanks depending on the subsequent use of the formed part.

 In addition, the deformation is carried out with respect to the median fiber of the metal constituting the sheet blank 1, to ensure uniform deformation and to maintain the accuracy of microperforations of the central part 2 of the sheet blank 1.

 During this stage of curvature formation, the upper part of the plate 42 is located under the peripheral zone 3 of the sheet blank. At the end of this stage, a controlled longitudinal bending of the free part 3 of the sheet blank 1, located between the punch 11 and the peripheral clamp, is realized. For this, the intermediate base plate 12 rests on the pins 22, and the peripheral part 3 of the sheet blank 1 under the influence of the springs 29 is held by a clamp. The localized zone of the upper 32 and lower 24 clamps act mechanically.

 This mechanical effect is realized by lowering the wedges 17 by means of the upper base plate 13 so that the wedge surface 21 is in contact with the wedge surface 30 of the upper clamp 23, which would lead to the convergence of the opposing upper 23 and lower 24 clamps.

 In addition, such a mechanical effect on each of the clamps 23 and 24 leads to the transfer through pins 33 of the pusher action to the peripheral part 3 of the sheet blank 1, which is original with respect to the classical stamping, which occurs under the action of a tensile force acting on the workpiece under the punch.

 Thus, the convergence of the upper and lower clamps 23 and 24 causes a controlled longitudinal bending on the peripheral part 3 of the sheet blank 1. This longitudinal bending, oriented and occurring around the middle fiber of the sheet stock 1, is performed so that the deformation of the peripheral part 3 of the sheet stock 1 corresponds to such a flow of metal at which the thickness and perimeter of the sheet stock 1 are kept constant.

 In the process of mechanical action on the clamps 23 and 24, their opposite sides are deformed (Fig. 8). The edges of the sheet stock 1 are pushed by pins 33.

 This mechanical effect also causes the simultaneous convergence of the two sections 43 and 48 of the plate 42 and the rise of the top of the plate 42.

 The combined movement of the rise and rapprochement of the plate 42 orientates the longitudinal bending of the peripheral part 3 of the sheet blank 1 located between the punch-matrix complex and clamps 23 and 24.

 Using the press slide, the lowering of the upper base plate 13 and the wedges 17 continues, with the lower wedge surface 19 coming into contact with the wedge portion 38 of the sliders 36. The clamp and the plate 42 are held in close position by the vertical side wall of the wedges 17 (Figs. 9 and 10).

 The next phase of the method consists in spreading part 3 of the sheet blank 1 by a portable movement during the simultaneous lowering of the clamps 23 and 24 and the plate 42. For this, the lowering of the upper base plate 13 and the wedges 17 is continued.

 The wedges 17 through the wedge surface 19 and the wedge section 38 impart a lateral movement to the sliders 36 against the force of the springs 41. The lateral movement of the creepers 36 reports simultaneous upward movement of the clamps 23 and 24 through the wedge section 39 and the wedge surface 37 of the frame 35 and the downward movement of the plate 42 through the wedge section 40 creepers 36 and a wedge surface 47 of a support 44.

 The angle of inclination of the wedge section 39 is greater than the angle of inclination of the wedge section 40, so that the vertical movement of the clamps is faster than the vertical movement of the plate 42.

 In the process of the last phase of the final processing of the edges, the end of the peripheral part 3 of the sheet blank 1 is pressed against the side wall of the punch 11 by lifting the plate 42.

 To this end, lowering of the upper base plate 13 and the wedges 17 is continued in order to continue the lateral movement of the sliders 36. The frame 35 is released under the wedge portion 39 of the sliders 36 to go to the upper surface 51, which leads to a stop of the downward movement of the clamps 23 and 24. On the other hand, the plate 42 continues to rise, since the end of the peripheral part 3 of the sheet blank 1 is pressed against the side wall of the punch 11.

 Then, the upper base plate 13 rises again, which entails the opening of the device by lifting the wedges 17, the intermediate base plate 12, the punch 11 and the upper clamp 23.

 Under the influence of the springs 41 and 50 of the crawler 36, the lower clip 24 and the plate 42 take their initial position.

 The master cylinder 10 is still held at bottom dead center to prevent the matrix 7 from rising again, which would lead to deformation of the formed sheet blank.

Claims (19)

 1. A method of forming a sheet preform by drawing the central part of the preform and acting on the flange, characterized in that the preform flange is placed between the deformable punch and the deformable matrix, the peripheral part of the preform flange is pressed at a limited width, the central part of the preform flange is clamped, and a central contour is formed part of the workpiece flange by setting the middle fiber of the workpiece flange in a specific position with respect to the neutral fiber of the knot punch matrix to the waist occurrences in at least limited areas of the workpiece flange of controlled internal stress, carry out longitudinal bending on the free part of the workpiece flange, controlled and oriented by moving the peripheral part of the workpiece flange, while maintaining a constant thickness and perimeter of the workpiece flange, and at the same time deploy the peripheral zone of the workpiece flange to obtain a bent edge .  2. The method according to claim 1, characterized in that in the process of longitudinal bending of the free part of the workpiece flange, the deformation of said free part is oriented.  3. A device for forming a sheet blank containing a matrix, a punch fixed to the upper plate by means of a traverse, and an annular peripheral clip, characterized in that the matrix and punch are made of a deformable material, and the device is equipped with a node of radial bias of the clamp, a node of vertical bias of the clamp and means for controlling the longitudinal bending and turning of the peripheral part of the workpiece flange along the side walls of the punch or die.  4. The device according to claim 3, characterized in that the peripheral clip consists of a lower clip and an upper clip mounted on a traverse.  5. The device according to p. 4, characterized in that the lower clip at the level of the upper peripheral edge is provided with a wedge surface.  6. The device according to claim 3, characterized in that the node of the radial displacement of the clip consists of wedges mounted on the upper plate.  7. The device according to claim 6, characterized in that the wedges have an end wedge surface and a side wedge surface for interacting with the wedge surface of the lower clip.  8. The device according to claim 3, characterized in that the node of the vertical bias of the clip consists of creepers interacting with the wedges, and a frame located between the said creeps and the clip.  9. The device according to claim 8, characterized in that the creepers are movable in a direction perpendicular to the direction of movement of the wedges.  10. The device according to claim 8, characterized in that the creepers contain on their upper wall several wedge sections with different angles of inclination and orientation.  11. The device according to claim 8, characterized in that the frame is provided at the level of its upper peripheral edge with a wedge surface having the same slope as one of the wedge surfaces of the crawler.  12. The device according to claim 3, characterized in that the means of controlling the longitudinal bending of the peripheral part of the workpiece flange along the sides of the punch is made in the form of a deformable peripheral plate.  13. The device according to p. 12, characterized in that the deformable plate is made in the form of a V-shaped flexible element, the first part of which rests on the punch matrix assembly, and the second on the clamp.  14. The device according to item 13, wherein the first part of the deformable plate is equipped with a stand in the form of a frame.  15. The device according to p. 14, characterized in that the stand has a vertical wall and a horizontal base adjacent to the edge of the said wall at a right angle.  16. The device according to p. 15, characterized in that the horizontal base of the stand has a wedge section with the same slope as the wedge section of the crawlers.  17. The device according to item 13, wherein the second part of the plate rests on the clamp through the pusher in the form of a vertical plate, the lower end of which is located on the horizontal base of the stand.  18. The device according to item 13, characterized in that it is provided with springs located between the vertical wall of the stand and the pusher.  19. The device according to claim 3, characterized in that it is equipped with means for blocking the matrix at bottom dead center.

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